Reusable and Highly Active Copper-Based Lacunary-type Polyoxometalate (LPMo-Cu) as an Effective Catalyst for Nitroarene Reduction in Aqueous Solution

Abstract

Lacunary polyoxometalates (LPOMs), a class of anionic metal oxide clusters, are promising materials as catalysts, photocatalysts, and electrocatalysts. Designing and functionalizing this type of compound are key factors for the discovery and development of novel materials. Herein, a new lacunary polyoxometalate-based compound was designed as a heterogeneous catalyst, prepared through functionalization of a lacunary Keggin-type polyoxometalate, i.e., [PMo11O39]7–, with 3-aminopropyltrimethoxysilane (APTS) and 2-pyridine carboxaldehyde. Subsequent reactions of this compound with Cu2+ ions led to the desired catalyst, LPMo-Cu. The catalytic activity of the obtained LPMo-Cu was examined in nitroarene reduction using sodium borohydride as a reducing agent in aqueous solution. It was specified that the synthesized LPMo-Cu exhibits high catalytic efficiency in the reduction of a wide variety of nitroarenes in a short time (5 min). Furthermore, the stability and recoverability of the prepared material were proved as a result of four consecutive reduction cycles without a significant decrease in its efficiency.

Lacunary Keggin-Type Phosphomolybdate Functionalized with Ru(acac)3 Complex for Electrocatalytic H2 Production in Aqueous Media

“…The high-resolution XPS of the N 1s and Mo 3p in Figure G illustrated a broad peak, which can be deconvoluted into two subpeaks at 398.2 and 397.5 eV ascribed to N 1s and Mo 3p 3/2 , respectively. , Furthermore, Mo 3p 1/2 is located at 416.5 eV. Finally, the high-resolution XPS of Mo 3d 5/2 and Mo 3d 3/2 showed two peaks at 232.3 and 236.5 eV standing for Mo (6+) oxidation state, respectively (Figure H) …”

“…However, a slight shift was observed as a result of the interaction of terminal oxygen (O t ) of PMo 11 with APTS (O t -Si) . Moreover, additional bands that appeared at about 2942 and 1383 cm –1 ascribed to C–H stretching and bending vibrations in the propyl chain, respectively. , In the FT-IR spectrum of PMo 11 –Ru(acac) 3 , the peaks of PMo 11 -APTS can be seen as well as CO (1653 cm –1 ) and CN (1522 cm –1 ) stretching vibrations of the acac ligands of attached Ru complex which affirms the formation of imine groups. , In addition, some peaks appeared in the 1300–1600 cm –1 region, which can be assigned to stretching vibrations in the acetylacetonato ligand …”

A stable hybrid catalyst (POM-PPPh3/L/Ni) for the reduction of toxic nitroarene compounds in water

“…1 Catalytic nitroarene reduction to aminoarenes is considered a great solution to overcome this problem. [2][3][4][5] The obtained aminoarenes have been introduced as effective intermediates in a large number of industries including pharmaceuticals, pigments and dyes, agrochemicals, and polymers. 2,6 Hence, turning these harmful pollutants into useful or harmless compounds through reduction and degradation processes is of great importance for conserving our planet.…”

“…23 A recent literature review demonstrates that catalysts based on polyoxometalates have been used for different catalytic reactions such as the reduction of nitroarenes. 4 For example, MacDonald et al showed that an electrochemically reduced POM (silicotungstic acid) is a selective catalyst to reduce a series of nitroarenes. 24 Kurbah and his coworkers synthesized a NiO@PolyMo nanocomposite and utilized this newly synthesized compound as a selective and efficient catalyst for the hydrogenation of nitroarenes.…”

Huge Electron Sponge of Polyoxometalate toward Advanced Lithium-Ion Storage

“…Polyoxometalates (POMs) are a class of nanostructured transition metal oxide molecular clusters with a clear composition, diverse structures, adjustable structure volume, flexible scaffolds, easy derivatization, adjustable valence state, and reversible redox properties. Therefore, they are attractively researched in electrochemical energy storage, , catalytic, , medicine, , photo/electro-chromics, − and nature . Different from the traditional transition metal oxides, POMs are able to store multiple electrons during the charging/discharging process, known as an “electron sponge”.…”